Adaptive Coding and Modulation (ACM) operates by adapting a modulation and forward error correction waveform that carries user data into discreet time sliced data blocks with varying degrees of symbol rate, modulation and error correction encoded per block (ModCod). An ACM scheme may also alter/adapt a symbol rate of the signal. The symbol rate may be adapted with or without adaptions to the modulation and error correction. In some embodiments, the symbol rate may be fixed and not subject to adaption.
Data delivered using lower order ModCods are more robust to signal degradation at the expense of consuming a higher amount of available forward direction bandwidth. Conversely, data delivered using higher order ModCods consumes less forward direction bandwidth at the expense of being less robust to signal degradation. Thus, there is an inverse relationship between bandwidth consumption and throughput performance
Prior art service plans are based on traffic priority and raw data usage, with all users allowed to operate on the ModCod necessary under current fade conditions. All users, regardless of service plan, are allowed to operate on the entire set of operational ModCods. These plans do not account for the bandwidth efficiency loss when large numbers of lower revenue users are forced by signal fade, for example, due to inclement weather conditions, to use less efficient higher availability coding rates. Under the signal fade subscribers on higher rate plans are penalized as less bandwidth is available. Adding ModCod restrictions to lower cost subscribers provides another dimension to the differentiation of services. When conditions are good, the system provides service to the entire set of subscribers in the mix, and as conditions deteriorate the system automatically sheds the lower cost/service level subscriber traffic.